Which of the following is true about Greedy algorithm?
- (A)
does not make any optimization
- (B)
makes local optimal decisions based on the selected criterion
- (C)
requires exhaustive search of all possible solutions
- (D)
is obvious in its correctness
ISRO CS 2025 Q.4: solution and answer
Answer and solution
ANSWER
The correct option is (b): a greedy algorithm makes locally optimal decisions based on the selected criterion.
Official answer: BSource: ISRO's final answer key of 15 May 2026
A greedy algorithm builds a solution step by step. At each step it picks the choice that looks best under a fixed selection criterion, and it never reconsiders that choice.
Option (a) is false: greedy methods are used for optimization problems. Examples are Huffman coding, Kruskal's and Prim's algorithms, and activity selection.
Option (b) matches the definition: each decision is locally optimal under the chosen criterion, such as the smallest edge weight or the earliest finish time.
Option (c) is false: exhaustive search of all possible solutions is brute force or backtracking, not greedy.
Option (d) is false: a greedy choice is not obviously correct. Correctness needs a proof, using the greedy-choice property and optimal substructure, and for some problems (such as 0/1 knapsack) a greedy strategy gives wrong answers.
So the only true statement is (b).
KEY IDEA
A greedy algorithm commits at every step to the locally best choice under a fixed criterion and never revisits it. It is an optimization technique, but its correctness must be proved for each problem.
WATCH OUT FOR
Assuming a greedy algorithm always gives the optimal answer (option d), or confusing it with exhaustive search or backtracking (option c). Greedy fails on problems such as 0/1 knapsack.
From the ISRO CS 2025 paper. Every question of this paper · The full paper (PDF, ISRO) · All 2 ISRO Design techniques questions, with notes